Bedfordshire Police Chief Constable Jon Boutcher, who is heading up the investigation into IRA agent Stakeknife

Significant new evidence has been uncovered by an English police chief investigating more than 50 murders linked to the Army's notorious IRA agent Stakeknife.

Victims' families have told stories never divulged before at the start of an independent probe by Bedfordshire Police Chief Constable Jon Boutcher into the high-ranking mole who led the IRA's "nutting squad" internal security unit while in the employ of the state.

A group of six international policing experts has been appointed to inform the investigation on a voluntary basis. They include senior police officers from the US, Scotland, an Australian ex-officer and ex-Northern Ireland police ombudsman Nuala O'Loan.

In 2003 Stakeknife was widely named as west Belfast man Freddie Scappaticci but he has always strongly denied the allegation.

Mr Boutcher said: "This week we have heard things that from what the families have told me they have never told anyone before, because nobody has asked them.

"What I have been told this week is significant evidence against the people responsible for these offences."

He has asked the victims' families to give him time to investigate and recover the evidence.

"It is incredible what I have heard.

"There is a pessimism which I understand, I completely get, because people felt let down and almost abandoned.

"It almost feels like their rights were taken away from them because of the nature of what happened to their loved ones.

"They have now got a voice and that is this investigation, and they told me of what they saw at that time that they have never been able to tell anybody before and we need people to do that."

The investigation is centred on possible crimes by paramilitaries, agents and Army and police handlers linked to Stakeknife, allegedly the military's highest-ranking spy within the IRA.

Multiple murders, attempted murders and unlawful imprisonments are included in the probe.

NYPD deputy commissioner for intelligence and counter-terrorism John Miller and Mike Downing, deputy chief of the Los Angeles Police Department, will be part of the expert advisory group.

It will also include Kathleen O'Toole, part of the Patten Commission which reformed policing in Northern Ireland.

Iain Livingstone, Deputy Chief Constable with Police Scotland, and Nick Kaldas, a former deputy commissioner of police in New South Wales who has been working with the UN on a Hezbollah probe in the Middle East, complete the group.

A second team of six victims' representatives have been appointed to address the needs of Stakeknife's alleged victims and their families. It includes: Alan McBride, bereaved in the IRA's Shankill Road fish shop bombing; Victims Commissioner Judith Thompson and Mary Fetchet, who founded Voices of September 11 following the death of her son at the World Trade Centre in 2001.

The Stakeknife investigation was launched after Northern Ireland's Director of Public Prosecutions Barra McGrory referred the multiple allegations to the Police Service of Northern Ireland (PSNI).

PSNI Chief Constable George Hamilton asked external police to undertake the probe in an effort to ensure its independence. No former or current officers who have served in Northern Ireland will work on the investigation, nor will ex or serving Ministry of Defence or Security Service personnel.

"Everyone, Republican or otherwise has their own particular part to play. No part is too great or too small, no one is too old or too young to do something."

~Bobby Sands 1954-1981~

'Mother Erin'

Two divine persons in one. A mother lamenting her children in bondage. A girl ravished by the Saxon, who weeps over her stringless harp. But her young champions keep watch in the mountains, awaiting the dawn of the bright sun of Freedom. They will gather around her with pikes and swords.